Transmitting/receiving apparatus using a plurality of spreading codes

ABSTRACT

Transmitting/receiving apparatuses are installed in a base station and a mobile station, respectively, to perform mutual transmission and reception by using a plurality of spreading codes. The transmitting/receiving apparatus installed in the base station has a block for designating to the mobile station the kind and the number of spreading codes used in a reverse link from the mobile station to the base station through a forward link at the time that communication with the mobile station is started. The transmitting/receiving apparatus installed in the mobile station has a block for transmitting a signal to the base station by using spreading codes of the designated kind and number. The transmitting/receiving apparatus installed in the base station further has a block for detecting receiving quality values of the signal transmitted from the mobile station with respect to individual spreading codes used in the mobile station, a block for deciding whether or not the detected receiving quality values exceed a prescribed quality value, and a block for finally setting the kind and number of spreading codes to be used in the reverse link on the basis of the spreading codes for which the detected receiving quality values are determined to exceed the prescribed quality value.

This is a division of application Ser. No. 08/814,029 filed Mar. 10,1997.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a transmitting/receiving apparatus forperforming transmission and reception by using a plurality of spreadingcodes and more particularly, to a transmitting/receiving apparatus whichcan increase and decrease the number of spreading codes in accordancewith a grade of link quality.

2. Description of the Related Art

A conventional example of a transmitting/receiving apparatus forperforming transmission and reception by using a plurality of spreadingcodes is shown in block diagram form in FIG. 1. When thetransmitting/receiving apparatus is installed in a base station whichcan afford to use 20 spreading codes for reverse and forward links,respectively, at a time, it operates as will be described below. Sincethis base station can use 20 spreading codes at a time, it canaccommodate 20 mobile stations using a single spreading code.

Firstly, the operation of a receiver of the transmitting/receivingapparatus will be described. By transferring a switch 202 to adown-converter 204, a receiving signal 203 received by an antenna 201 isinputted to the down-converter 204. In the down-converter 204, a carrierfrequency of the receiving signal 203 is down-converted into an IFfrequency, so that the receiving signal 203 is converted into an IFsignal 205. In a quadrature detector 206, the IF signal 205 from thedown-converter 204 is quadrature-detected, so that the IF signal 205 isconverted into an in-phase signal (I-ch) 207 and a quadrature signal(Q-ch) 208. The in-phase signal 207 and quadrature signal 208 areinputted to analog/digital converters (A/D converters) 213 and 214 vialow-pass filters (LPF's) 209 and 210 so as to be converted into adigital in-phase signal 215 and a digital quadrature signal 216,respectively. The LPF's 209 and 210 are used to suppress frequencycomponents in the in-phase and quadrature signals 207 and 208 which are½ or more of a sampling frequency in the A/D converters 213 nd 214 andto shape waveforms of the in-phase and quadrature signals 207 and 208.The digital in-phase signal 215 and digital quadrature signal 216delivered out of the A/D converters 213 and 214 are inputted to 20demodulating units 217 ₁ to 217 ₂₀. First to twentieth codes 227, whichare identical to the 20 spreading codes used during transmission, aregenerated by a reception code generator 226 and inputted one by one tothe demodulating units 217 ₁ to 217 ₂₀. The demodulating unit 217 ₁includes despreaders 218 ₁ and 219 ₁ for multiplying the first code 227which is identical to the first one of the 20 spreading codes usedduring transmission by the digital in-phase signal 215 and the digitalquadrature signal 216, respectively, to reproduce two transmittingsymbols 220 ₁ and 221 ₁, a decoder 222 ₁ for decoding the two reproducedtransmitting symbols to a bit signal 223 ₁, and a frame decomposer 224 ₁for deriving information concerning the kind and the number of thespreading codes from a frame format contained in the bit signal 223 ₁and delivering receiving data 225 of the first code. The remainingdemodulating units 217 ₂ to 217 ₂₀ are constructed similarly to thedemodulating unit 217 ₁.

Next, the operation of a transmitter of the transmitting/receivingapparatus will be described. In a frame assembler 229, transmitting data228 is arranged in a frame format in accordance with the number ofspreading codes used and a data amount of the transmitting data 228. Ina transmission code generator 236, spreading codes 237 to be used aredetermined on the basis of information concerning the spreading codesand spreading code information owned by the base station which are sentfrom each of the demodulating units 217 ₁ to 217 ₂₀. Transmittinginformation pieces 230 delivered out of the frame assembler 229 areinputted to 20 modulating units 231 ₁ to 231 ₂₀. The modulating unit 231₁ has a modulator 232 ₁ for mapping the transmitting information to anin-phase signal (I-ch) 233 ₁ and a quadrature signal (Q-ch) 234 ₁, andspreaders 235 ₁ and 235 ₂ for spread-processing the in-phase signal 233₁ and the quadrature signal 234 ₁ by using one of the spreading codes237. The remaining modulating units 231 ₂ to 231 ₂₀ are constructedsimilarly to the modulating unit 231 ₁. Output signals 238 and outputsignals 239 from the modulating units 231 ₁ to 231 ₂₀ are added byadders 240 and 241, respectively. Output signals 242 and 243 of theadders 240 and 241 are converted from digital signals to analog signalsby means of digital/analog converters (D/A converters) 244 and 245,respectively. Output signals 246 and 247 of the D/A converters 244 and245 are inputted to a quadrature modulator 252 via LPF's 248 and 249,respectively, so that a base-band signal is converted into an IF signal253. The LPF's 248 and 249 are adapted to eliminate higher harmoniccomponents in the output signals 246 and 247 of the D/A converters 244and 245 and to shape waveforms of the output signals 246 and 247 of theD/A converters 244 and 245. The IF signal is up-converted from the IFfrequency to a carrier frequency by means of an up-converter 254 so asto be converted into a transmitting signal 255. The transmitting signal255 is inputted to the antenna 201 via the switch 202 and transmitted tothe mobile station.

In the aforementioned transmitting/receiving apparatus, however,transmitting data pieces are transmitted while being superimposed oneach other by using plurality of spreading codes and as compared to atransmitting/receiving apparatus adapted to transmit transmitting databy using a single spreading code, the service area is disadvantageouslynarrowed for the following reasons:

(1) Much transmitting power is required for transmission over the samedistance; and

(2) The transmitting distance is reduced when the transmitting power ismade to be equal for the both types of apparatuses.

SUMMARY OF THE INVENTION

An object of the present invention is to provide atransmitting/receiving apparatus using a plurality of spreading codeswhich can expand the service area.

In a transmitting/receiving apparatus using a plurality of spreadingcodes according to the present invention, quality of a transmittingsignal from a mobile station (hereinafter referred to as a reverse linksignal) is examined in a base station and when the quality of thereverse link signal is bad, the number of spreading codes to be used isdecreased but on the other hand, when the quality of the reverse linksignal is good, the number of spreading codes to be used is increased.An upper limit of the number of spreading codes is set to a valueprescribed by the system.

In a transmitting/receiving apparatus using a plurality of spreadingcodes according to the present invention, quality of a transmittingsignal from a base station (hereinafter referred to as a forward linksignal) is examined in a mobile station and when the quality of theforward link signal is bad, the number of spreading codes to be used isdecreased but on the other hand, when the quality of the forward linksignal is good, the number of spreading codes to be used is increased.An upper limit of the number of spreading codes is set to a valueprescribed by the system.

More specifically, a first transmitting/receiving apparatus using aplurality of spreading codes according to the present invention isrepresented by transmitting/receiving apparatuses installed in a basestation and a mobile station, respectively, to perform mutualtransmission and reception by using a plurality of spreading codes,

the transmitting/receiving apparatus installed in the base stationcomprises means for designating to the mobile station the kind and thenumber of spreading codes to be used in a reverse link from the mobilestation to the base station through a forward link from the base stationto the mobile station at the time that communication with the mobilestation is started,

the transmitting/receiving apparatus installed in the mobile stationcomprises means for transmitting a signal to the base station by usingthe spreading codes of the designated kind and number, and

the transmitting/receiving apparatus installed in the base stationfurther comprises means for detecting receiving quality values of thesignal transmitted from the mobile station with respect to individualspreading codes used in the mobile station, means for deciding whetherthe detected receiving quality values exceed a prescribed quality value,and means for finally setting the kind and the number of spreading codesto be used in the reverse link on the basis of spreading codes for whichthe detected receiving quality values are determined to exceed theprescribed quality.

A second transmitting/receiving apparatus using a plurality of spreadingcodes according to the present invention is represented bytransmitting/receiving apparatuses installed in a base station and amobile station, respectively, to perform mutual transmission andreception by using a plurality of spreading codes,

the transmitting/receiving apparatus installed in the base stationcomprises means for designating to the mobile station the kind and thenumber of spreading codes to be used in a forward link from the basestation to the mobile station through the forward link at the time thatcommunication with the mobile station is started, and means fortransmitting a signal to the mobile station by using the spreading codesof the designated kind and number, and

the transmitting/receiving apparatus installed in the mobile stationcomprises means for detecting receiving quality values of the signaltransmitted from the base station with respect to individual spreadingcodes, means for deciding whether the detected receiving quality valuesexceed a prescribed quality value, and means for finally setting thekind and the number of spreading codes to be used in the forward link onthe basis of spreading codes for which the detected receiving qualityvalues are determined to exceed the prescribed quality value.

A third transmitting/receiving apparatus using a plurality of spreadingcodes according to the present invention is represented by atransmitting/receiving apparatus for performing transmission andreception by using a plurality spreading codes, and thetransmitting/receiving apparatus comprises:

means for detecting quality values of a receiving signal with respect toindividual spreading codes;

means for deciding whether or not the detected quality values exceed aprescribed quality value; and

means for making a request for re-transmission of spreading codes forwhich the detected quality values are determined to be below theprescribed quality value.

A fourth transmitting/receiving apparatus using a plurality of spreadingcodes according to the present invention is represented by atransmitting/receiving apparatus for performing transmission andreception of voice and data by using a plurality of spreading codes, andthe transmitting/receiving apparatus comprises:

means for detecting whether or not the voice is in a soundless state;and

means for using spreading codes used in transmission of the voice foruse in transmission of the data when the voice is determined to be inthe soundless state.

A fifth transmitting/receiving apparatus using a plurality of spreadingcodes according to the present invention is represented by atransmitting/receiving apparatus for performing transmission andreception of voice required of real time nature and data not required ofreal time nature by using a plurality of spreading codes, and thetransmitting/receiving apparatus comprises:

means for designating more spreading codes for transmission of the datathan for transmission of the voice to a forward link from a base stationto a mobile station; and

means for transmitting a control signal for a request forre-transmission of the data by using a reverse link for voice from themobile station to the base station.

A sixth transmitting/receiving apparatus using a plurality of spreadingcodes according to the present invention is represented by atransmitting/receiving apparatus for performing transmission andreception of voice required of real time nature and data not required ofreal time nature by using a plurality of spreading codes, and thetransmitting/receiving apparatus comprises:

means for designating more spreading codes for transmission of the datathan for transmission of the voice to a reverse link from a mobilestation to a base station; and

means for transmitting a control signal for a request forre-transmission of the data by using a forward link for voice from thebase station to the mobile station.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a conventional example of atransmitting/receiving apparatus for performing transmission andreception by using a plurality of spreading codes.

FIG. 2 is a block diagram showing the construction of a base stationside transmitting/receiving apparatus according to a first embodiment ofthe present invention.

FIG. 3 is a block diagram showing the construction of a mobile stationside transmitting/receiving apparatus according to the first embodimentof the present invention.

FIG. 4 is a flow chart for explaining the operation of thetransmitting/receiving apparatus according to the first embodiment ofthe present invention.

FIG. 5 is a flow chart for explaining the operation of atransmitting/receiving apparatus according to a second embodiment of thepresent invention.

FIG. 6 is a flow chart for explaining the operation of atransmitting/receiving apparatus according to a third embodiment of thepresent invention.

FIG. 7 is a flow chart for explaining the operation of atransmitting/receiving apparatus according to a fourth embodiment of thepresent invention.

FIG. 8 is a flow chart for explaining the operation of atransmitting/receiving apparatus according to a fifth embodiment of thepresent invention.

FIG. 9 is a flow chart for explaining the operation of atransmitting/receiving apparatus according to a sixth embodiment of thepresent invention.

FIG. 10 is a flow chart for explaining the operation of thetransmitting/receiving apparatus according to the sixth embodiment ofthe present invention.

FIG. 11 is a flow chart for explaining the operation of atransmitting/receiving apparatus according to a seventh embodiment ofthe present invention.

FIGS. 12A-12D illustrate frame formats used in thetransmitting/receiving apparatus according to the seventh embodiment ofthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

A base station side transmitting/receiving apparatus according to afirst embodiment of the present invention is installed in a base stationof CDMA system. The base station can afford to use 20 spreading codesfor reverse and forward links, respectively, at a time. Namely, the basestation can accommodate 20 mobile stations each using a single spreadingcode.

As shown in FIG. 2, a receiver of the base station sidetransmitting/receiving apparatus of the present embodiment comprises anantenna 1, a switch 2, a down-converter 4, a quadrature detector 6, twolow-pass filters (LPF's) 9 and 10, two analog/digital converters (A/Dconverters) 13 and 14, twenty demodulating units 17 ₁ to 17 ₂₀, areception code generator 28, and a code number assigning sequenceprocessor 30. The demodulating unit 17 ₁ includes two despreaders 18 ₁and 19 ₁, a decoder 22 ₁, a frame decomposer 25 ₁, and a qualitypresumer 24 ₁. The remaining demodulating units 17 ₂ to 17 ₂₀ areconstructed similarly to the demodulating unit 17 ₁.

A transmitter of the base station side transmitting/receiving apparatusof the present embodiment comprises a frame assembler 33, twentymodulating units 35 ₁ to 35 ₂₀, a transmission code generator 41, twoadders 45 and 46, two digital/analog converters (D/A converters) 49 and50, two low-pass filters (LPF's) 53 and 54, a quadrature modulator 57,and an up-converter 59. The modulating unit 35 ₁ includes a modulator 36₁ and two spreaders 39 ₁ and 40 ₁. Each of the remaining modulatingunits 35 ₂ to 35 ₂₀ is constructed similarly to the modulating unit 35₁.

The operation of the receiver of the base station sidetransmitting/receiving apparatus according to the present embodimentwill be described. By transferring the switch 2 to the down-converter 4,a receiving signal 3 received by the antenna 1 is inputted to thedown-converter 4. In the down-converter 4, a carrier frequency of thereceiving signal 3 is down-converted to an IF frequency, so that thereceiving signal 3 is converted into an IF signal 5. In the quadraturedetector 6, the IF signal 5 from the down-converter 4 isquadrature-detected, so that the IF signal 5 is converted into anin-phase signal (I-ch) 7 and a quadrature signal (Q-ch) 8. The in-phasesignal 7 and quadrature signal 8 are inputted to A/D converters 13 and14 via the LPF's 9 and 10 so as to be converted into a digital in-phasesignal 15 and a digital quadrature signal 16, respectively. The LPF's 9and 10 are used to suppress frequency components in the in-phase andquadrature signals 7 and 8 which are ½ or more of a sampling frequencyin the A/D converters 13 and 14 and to shape waveforms of the in-phaseand quadrature signals 7 and 8. The digital in-phase signal 15 and thedigital quadrature signal 16 delivered out of the A/D converters 13 and14 are inputted to the 20 demodulating units 17 ₁ to 17 ₂₀. First totwentieth codes 29, which are identical to the 20 spreading codes usedduring transmission, are generated by the reception code generator 28and inputted one by one to the demodulating units 17 ₁ to 17 ₂₀. In theespreaders 18 ₁ and 19 ₁ in the demodulating unit 17 ₁, the first code29 which is identical to the first one of the 20 spreading codes usedduring transmission is multiplied by the digital in-phase signal 15 andthe digital quadrature signal 16, so that two transmitting symbols 20 ₁and 21 ₁ are reproduced. The thus reproduced two transmitting symbols 20₁ and 21 ₁ are decoded to a bit signal 23 ₁ by means of the decoder 22₁. In the frame decomposer 25 ₁, information regarding the kind and thenumber of the spreading codes is derived from a format contained in thebit signal 23 ₁ and received data 26 of the first code is formed whichin turn is delivered out of the frame decomposer 25 ₁. The remainingdemodulating units 17 ₂ to 17 ₂₀ operate similarly to the demodulatingunit 17 ₁.

In the quality presumer 24 ₁, receiving quality (link quality) isexamined using the bit signal 23 ₁. For examination of the receivingquality, the following methods can be enumerated.

(a) Determination using the phase likelihood of reproduced symbols afterdespread.

The receiving quality is examined on the basis of a phase differencebetween transmitting and receiving signals.

(b) Determination using the likelihood of reproduced symbols afterdespread.

The receiving quality is examined on the basis of a vector error(likelihood) between transmitting and receiving signals.

(c) Determination based on CRC

In the base station side transmitting/receiving apparatus of the presentembodiment, the receiving quality is examined using the determinationbased on CRC.

In the code number assigning sequence processor 30, the informationconcerning the kind and the number of the spreading codes sent from theframe decomposers 25 ₁ to 25 ₂₀ of the decoding units 17 ₁ to 17 ₂₀ andthe information concerning the receiving quality sent from the qualitypresumers 24 ₁ to 24 ₂₀ are used to perform assignment of the kind(contents) and the number of the spreading codes. Details of theassignment will be described hereinafter in connection with an operationto be described later carried out between the base station sidetransmitting/receiving apparatus and mobile station sidetransmitting/receiving apparatus according to the present embodiment.

The operation of the transmitter of the base station sidetransmitting/receiving apparatus of the present embodiment will bedescribed. In the frame assembler 33, transmitting data 32 is arrangedin a frame format in accordance with the number of the spreading codes(signal 31) and a data amount of the transmitting data 32. In thetransmission code generator 41, spreading codes 42 to be used aredetermined on the basis of the kind and the number of the spreadingcodes (signal 31) sent from the code number assigning sequence processor30. Transmitting information pieces 34 delivered out of the frameassembler 33 are inputted to the 20 modulating units 35 ₁ to 35 ₂₀. Inthe modulator 36 ₁ of the modulating unit 35 ₁, the transmittinginformation 34 is mapped to an in-phase signal (I-ch) 37 ₁ and aquadrature signal (Q-ch) 38 ₁. In the spreaders 39 ₁ and 40 ₁, one ofthe spreading codes 42 sent from the transmission code generator 41 isused to spread-process the in-phase signal 37 ₁ and the quadraturesignal 38 ₁. The remaining modulating units 35 ₂ to 35 ₂₀ operatesimilarly to the modulating unit 35 ₁. Output signals 43 and outputsignals 44 from the modulating units 35 ₁ to 35 ₂₀ are added by theadders 45 and 46, respectively. Output signals 47 and 48 of the adders45 and 46 are converted from digital signals to analog signals by meansof the D/A converters 49 and 50, respectively. Output signals 51 and 52of the D/A converters 49 and 50 are inputted to the LPF's 53 and 54,respectively. Output signals 55 and 56 of the LPF's 53 and 54 areinputted to the quadrature modulator 57, so that a base-band signal isconverted into an IF signal 58. The LPF's 53 and 54 are adapted toeliminate higher harmonic components in the output signals 51 and 52 ofthe D/A converters 49 and 50 and to shape waveforms of the outputsignals 51 and 52 of the D/A converters 49 and 50. The IF signal 58 isup-converted from the IF frequency to a carrier frequency by means ofthe up-converter 59 so as to be converted into a transmitting signal 60.The transmitting signal 60 is inputted to the antenna 1 via the switch 2and transmitted to the mobile station.

A mobile station side transmitting/receiving apparatus according to thefirst embodiment of the invention can afford to use maximally threespreading codes for reverse and forward links, respectively, at a time.As shown in FIG. 3, the mobile station side transmitting/receivingapparatus is constructed similarly to the aforementioned base stationside transmitting/receiving apparatus according to the presentembodiment but differs therefrom in the number of spreading codes to beused and the operation of a code number assigning sequence processor130.

The operation of a receiver of the mobile station sidetransmitting/receiving apparatus according to the present embodimentwill be described. By transferring a switch 102 to a down-converter 104,a receiving signal 103 received by an antenna 101 is inputted to thedown-converter 104. In the down-converter 104, a carrier frequency ofthe receiving signal 103 is down-converted to an IF frequency, so thatthe receiving signal 103 is converted into an IF signal 105. In aquadrature detector 106, the IF signal 105 from the down-converter 104undergoes quadrature detection so as to be converted into an in-phasesignal (I-ch) 107 and a quadrature signal (Q-ch) 108. The in-phasesignal 107 and the quadrature signal 108 are inputted to A/D converters113 and 114 via LPF's 109 and 110 so as to be converted into a digitalin-phase signal 115 and a digital quadrature signal 116, respectively.The LPF's 109 and 110 are used to suppress frequency components of thein-phase signal 107 and quadrature signal 108 which are ½ or more of asampling frequency in the A/D converters 113 and 114 and to shapewaveforms of the in-phase and quadrature signals 107 and 108. Thedigital in-phase signal 115 and the digital quadrature signal 116delivered out of the A/D converters 113 and 114 are inputted to 3demodulating units 117 ₁ to 117 ₃. First to third codes 129, which areidentical to three of 20 spreading codes used during transmission, aregenerated by a reception code generator 128 and inputted one by one tothe demodulating units 117 ₁ to 117 ₃. In despreaders 118 ₁ and 119 ₁ ofthe demodulating unit 117 ₁, the digital in-phase signal 115 and thedigital quadrature signal 116 are multiplied by the first code 129 whichis identical to the first one of the 3 spreading codes to reproduce twotransmitting symbols 120 ₁ and 121 ₁. The thus reproduced transmittingsymbols 120 ₁ and 121 ₁ are decoded to a bit signal 123 ₁ by means of adecoder 122 ₁. In a frame decomposer 125 ₁, information concerning thekind and the number of the spread codes is derived from a frame formatcontained in the bit signal 123 ₁ and at the same time receiving data126 of the first code is formed and delivered. The remaining decodingunits 117 ₂ and 117 ₃ operate similarly to the decoding unit 117 ₁.

In a quality presumer 124 ₁, receiving quality (link quality) isexamined using the bit signal 123 ₁. For determination of the receivingquality, the following methods can be enumerated.

(a) Determination using the phase likelihood of reproduced symbols afterdespread.

(b) Determination using the likelihood of reproduced symbols afterdespread.

(c) Determination based on CRC.

In the mobile station side transmitting/receiving apparatus according tothe present embodiment, the receiving quality is examined using thedetermination based on CRC.

In the code number assigning sequence processor 130, assignment of thekind and the number of the spreading codes is performed using theinformation concerning the kind and the number of the spreading codeswhich is sent from the frame decomposers 125 ₁ to 125 ₃ of thedemodulating units 117 ₁ to 117 ₃ and the information concerning thereceiving quality which is sent from the quality presumers 124 ₁ to 124₃. Details of the assignment will be described hereinafter in connectionwith an operation to be described later carried out between the basestation side transmitting/receiving apparatus and the mobile stationside transmitting/receiving apparatus according to the presentembodiment.

The operation of a transmitter of the mobile station sidetransmitting/receiving apparatus according to the present embodimentwill be described. In a frame assembler 133, transmitting data 132 isarranged in a frame format in accordance with the number of thespreading codes (signal 131) sent from the code number assigningsequence processor 130 and a data amount of the transmitting data 132.In a transmission code generator 141, spreading codes 142 to be used aredetermined on the basis of the kind and the number of the spreadingcodes (signal 131) sent from the code number assigning sequenceprocessor 130. Transmitting information pieces 134 delivered out of theframe assembler 133 are inputted to 3 modulating units 135 ₁ to 135 ₃.In a modulator 136 ₁ of the modulating unit 135 ₁, the transmittinginformation 134 is mapped to an in-phase signal (I-ch) 137 ₁ and aquadrature signal (Q-ch) 138 ₁. Spreaders 139 ₁ and 140 ₁ use one of the3 spreading codes 142 sent from the transmission code generator 141 tospread-process the in-phase and quadrature signals 137 ₁ and 138 ₁. Theremaining modulating units 135 ₂ and 135 ₃ operate similarly to themodulating unit 135 ₁. Output signals 143 and output signals 144 of themodulating units 135 ₁ to 135 ₃ are added by means of adders 145 and146, respectively. Output signals 147 and 148 of the adders 145 and 146are converted from digital signals to analog signals by means of D/Aconverters 149 and 150, respectively. Output signals 151 and 152 of theD/A converters 149 and 150 are inputted to LPF's 153 and 154,respectively. Output signals 155 and 156 of the LPF's 153 and 154 areinputted to a quadrature modulator 157, so that a base-band signal isconverted into an IF signal 158. The LPF's 153 and 154 are adapted toeliminate higher harmonic components in the output signals 151 and 152of the D/A converters 149 and 150 and to shape waveforms of the outputsignals 151 and 152 of the D/A converters 149 and 150. The IF signal 158is up-converted from an IF frequency to a carrier frequency by means ofan up-converter 159 so as to be converted into a transmitting signal160. The transmitting signal 160 is inputted to the antenna 101 via theswitch 102 and transmitted to the mobile station.

Referring now to FIG. 4, a method of determining the number of spreadingcodes at the time that transmission is started in an operation betweenthe base station side transmitting/receiving apparatus according to thepresent invention and the mobile station side transmitting/receivingapparatus according to the present invention will be described. Here, adescription will be given of the case where the base station requeststhe mobile station to perform transmission using three kinds ofspreading codes through a forward link but the description can beapplied similarly to the case where the mobile station requests the basestation to perform transmission using three kinds of spreading codes.

First Process

When the base station requests the mobile station to preform forwardlink transmission using three kinds of spreading codes, the kind and thenumber of the spreading codes are transmitted from the base station sidetransmitting/receiving apparatus to the mobile station sidetransmitting/receiving apparatus through the forward link. When themobile station requests the base station to perform transmission usingthree kinds of spreading codes, the transmission request is received bythe base station and the kind and the number of the spreading codes aretransmitted from the base station side transmitting/receiving apparatusto the mobile station side transmitting/receiving apparatus a forwardlink.

Second Process

In the mobile station side transmitting/receiving apparatus, thereceiver applies despread and decoding processes to a receiving signalto reproduce transmitting symbols. The reproduced transmitting symbolsare channel-decoded and the kind and the number of transmitted spreadingcodes are inputted to the code number assigning sequence processor 130.In the code number assigning sequence processor 130, transmitting datais assigned to a frame format in accordance with the kind and the numberof the spreading codes. In the transmission code generator 128,maximally three spreading codes are generated on the basis of the kindand the number of spreading codes to be used in the next transmission. Atransmitting signal is mapped to an in-phase signal and a quadraturesignal which in turn are spread and then transmitted to the base stationside transmitting/receiving apparatus.

Third Process

In the base station side transmitting/receiving apparatus, thetransmitting signal (reverse link signal) using a plurality of spreadingcodes transmitted from the mobile station side transmitting/receivingapparatus is received and subjected to despread and decoding processesso as to reproduce transmitting symbols (step S1). Subsequently, thetransmitting symbols reproduced every spreading code are subjected tothe aforementioned receiving quality presumption process (step S2). Aresult of the receiving quality presumption obtained every spreadingcode is sent to the code number assigning sequence processor 30 andcompared with a prescribed value (step S3). The kind and the number ofspreading codes for which the result values of receiving qualitypresumption are determined to exceed the prescribed value are sent tothe frame assembler 33. In the frame assembler 33, the kind and thenumber of the sent spreading codes are applied to the frame format (stepS5). On the other hand, when the receiving quality is determined not tosatisfy desired quality with respect to all of the spreading codes and avalue of the number of spreading codes set during the previoustransmission is larger than 1 (one), a predetermined number issubtracted from the previous set value and the number and the kind ofresiduary spreading codes are sent to the frame assembler 33. In theframe assembler 33, the kind and the number of the sent spreading codesare applied to the frame format. In this case, since the mobile stationmust cooperate with the base station side transmitting/receivingapparatus to renewedly set the number and the kind of the sent spreadingcodes, the aforementioned second process is repeated (step S4). When thereceiving quality is determined not to satisfy desired quality withrespect to all of the spreading codes and a value of the number ofspreading codes set during the previous transmission is 1, the kind(contents) of the spreading code is sent to the frame assembler 33. Inthe frame assembler 33, the kind and the number of the sent spreadingcode are applied to the frame format (step S4).

Fourth Process

In the mobile station side transmitting/receiving apparatus, thereceiver receives the forward link signal transmitted from the basestation side transmitting/receiving apparatus and applies despread anddecoding processes to the receiving signal to reproduce transmittingsymbols. The reproduced transmitting symbols are channel-decoded and thekind and the number of sent spreading codes are inputted to the codenumber assigning sequence processor 130. In the code number assigningsequence processor 130, transmitting data is assigned to the frameformat in accordance with the kind and the number of the spreadingcodes. In the transmission code generator 128, maximally three spreadingcodes are generated on the basis of the kind and the number of spreadingcodes to be used in the next transmission. The transmitting signal ismapped to an in-phase signal and a quadrature signal which in turn arespread and then transmitted to the base station sidetransmitting/receiving apparatus (steps S5 and S6). Subsequently,transmission/reception is carried out using the kind and the number ofthe spreading codes (step 7).

As described above, by taking into account the fact that the distanceover which the electric wave delivered at the same power can propagateis shorter in the case of transmission effected using a plurality ofspreading codes than in the case of transmission effected using a singlespreading code, the presumption of the receiving quality is performedevery spreading code in the base station side transmitting/receivingapparatus to determine the number of spread codes assigned to a reverselink from the mobile station to the base station and thereaftertransmission/reception is carried out in the operation effected betweenthe base station side transmitting/receiving apparatus according to thepresent embodiment and the mobile station side transmitting/receivingapparatus. Through this, a great number of signals can be transmittedwhile satisfying the prescribed receiving quality.

Second Embodiment

In the transmitting/receiving apparatus according to the firstembodiment described as above, the quality of a receiving signal fromthe mobile station is examined in the base station at the time thatcommunication between the base station and the mobile station is startedto finally set the kind and the number of spreading codes to beassigned. But in mobile communication, the mobile station moves to causethe distance between the base station and the mobile station to changeand in consequence, the communication quality changes every moment. Inaddition, as the location where the mobile station is present changes,the communication quality also changes.

In a transmitting/receiving apparatus according to a second embodimentof the present invention, the kind and the number of spread codes areassigned in accordance with the communication quality which changesevery moment and hence the optimum kind and number of spreading codescan be assigned adaptively in the base station. A base station sidetransmitting/receiving apparatus and a mobile station sidetransmitting/receiving apparatus according to the second embodiment ofthe present invention are constructed similarly to thepreviously-described base station side transmitting/receiving apparatusand mobile station side transmitting/receiving apparatus according tothe first embodiment and therefore, the operation of the base stationside transmitting/receiving apparatus and mobile station sidetransmitting/receiving apparatus according to the second embodiment ofthe present invention will be described with reference to a flow chartshown in FIG. 5.

First Process

In the base station, a reverse link signal from the mobile station isreceived at a time point during communication and the receiving signalis subjected to despread and decoding processes to reproducetransmitting symbols (step S11). When the number (L) of spreading codesto be assigned to the reverse link is 1, the program proceeds to asecond process to be described below and when the number (L) ofspreading codes to be assigned is larger than 2, the program proceeds toa third process to be described later (step S12).

Second Process

When a predetermined time (first setting value) has elapsed followingdetermination that the number (L) of spreading codes to be assigned tothe reverse link is 1 (namely, when counter value T1=first settingvalue), transmission is requested with the kind of spreading codeschanged to K and thereafter, the counter is reset (steps S13 to S15). Onthe other hand, when the predetermined time (first setting value) hasnot elapsed following determination that the number (L) of spreadingcodes to be assigned to the reverse link is 1, transmission is requestedwith the kind of spreading codes kept to be one and thereafter thecounter is incremented (steps S16 and S17). Subsequently, the programproceeds to the normal transmitting/receiving mode and the procedureends (step S19).

Third Process

Presumption of receiving quality using determination based on, forexample, CRC is performed every spreading code (step S20) to determinethe number (N) of spread codes having receiving quality values whichexceed a prescribed value. When the determined number (N) is 0,transmission is requested with the kind of spreading codes kept to be apreset value (M) (steps S21 and S22). When the determined number (N) islarger than 0 and is smaller than the number (L) of spreading codes tobe assigned to the reverse link (namely, when 0<N<L) or when thedetermined number (N) equals the number (L) of spreading codes to beassigned to the reverse link and equals a maximum (Nmax) of the numberof spreading codes to be assigned to the reverse link (namely, when N=Land N=Nmax), transmission is requested with the kind (for example, whenthe spreading code is of an M series, a length of the M series) set to N(steps S21 and S23). Further, when the determined number (N) is equal tothe number (L) of spreading codes to be assigned to the reverse link andis smaller than the maximum (Nmax) of the number of spreading codes tobe assigned to the reverse link (namely, when N=L and N<Nmax), a processas below is carried out. More particularly, when a predetermined time(second setting value) has elapsed following setting of the number ofspreading codes to be assigned to L (namely, when counter valueT2=second setting value), transmission is requested with the kind ofspreading codes changed to L+1 (steps S21, S24 and S25) and thereafterthe counter is reset (step S26). On the other hand, when thepredetermined time (second setting value) has not elapsed followingsetting of the number of spreading codes to be assigned to L,transmission is requested with the kind of spreading codes kept to be L(steps S21, S24 and S27) and thereafter, the counter is incremented(step S28). After the above steps S22, S23, S26 and S28 end, the programproceeds to the normal transmitting/receiving mode and the procedureends (step S19).

As described above, in the transmitting/receiving apparatus according tothe second embodiment of the present invention, for the purpose ofmaintaining the predetermined communication quality against even achange in reverse link quality due to movement of the mobile stationduring communication, the communication quality of reverse link ispresumed in the base station and the kind and the number of spreadingcodes are adaptively controlled in accordance with the presumedcommunication quality. Further, the time required for communication canbe decreased by increasing the kind and the number of spreading codes tobe assigned when the link quality is improved.

Third Embodiment

A base station side transmitting/receiving apparatus and a mobilestation side transmitting/receiving apparatus according to a thirdembodiment of the present invention are constructed similarly to thepreviously-described base station side transmitting/receiving apparatusand mobile station side transmitting/receiving apparatus according tothe first embodiment and therefore, the operation of the base stationside transmitting/receiving apparatus and mobile station sidetransmitting/receiving apparatus according to the third embodiment willbe described with reference to a flow chart shown in FIG. 6. In anoperational example shown in the flow chart, forward link transmissionfrom the base station to the mobile station is requested using threekinds of spreading codes but a request for transmission from the mobilestation to the base station using three kinds of spreading codes can befulfilled similarly.

First Process

The kind and the number of spreading codes are transmitted from the basestation to the mobile station through a forward link. But in the casewhere the mobile station makes a request, the transmission request fromthe base station is first received and thereafter, the kind and thenumber of spreading codes are transmitted from the mobile station to thebase station through a reverse link.

Second Process

In the mobile station, the forward link signal from the base station isreceived and thereafter, the receiving signal is subjected to despreadand decoding processes to reproduce transmitting symbols (step S40).Subsequently, the mobile station carries out channel-decoding to obtainthe number and the kind of spreading codes transmitted from the basestation (step S41) and waits for the next forward link signal.

Third Process

In the base station, the kind and the number of spreading codestransmitted to the mobile station are used to transmit a transmittingsignal to the mobile station through the forward link.

Fourth Process

In the mobile station, the forward link signal from the base station isreceived and the receiving signal is subjected to despread and decodingprocesses to reproduce transmitting symbols (step S42). Thereafter, inthe mobile station, receiving quality presumption using, for example,the determination based on CRC is carried out every spreading codes(step S43). Results of the presumption are sent to the code numberassigning sequence processor 130 (see FIG. 3). In the code numberassigning sequence processor 130, the kind and the number of spreadingcodes having receiving quality values which exceed a prescribed valueare determined and the results are sent to the frame assembler 133. Inthe frame assembler 133, when the number (N) of spreading codes havingreceiving quality values exceeding the prescribed value is one or more,a request for transmission using N kinds of spreading codes istransmitted to the base station through the reverse link (steps S44 andS45). On the other hand, the receiving quality values are below theprescribed value with respect to all of the spreading codes, the number(M) of spreading codes to be transmitted presently is determined bysubtracting a predetermined number from the previous setting number anda request for transmission using spreading codes of the determinednumber and kind is transmitted to the base station through the reverselink (steps S44 and S46). At that time, when the determined number (M)of spreading codes to be transmitted presently is 1, a request fortransmission using one kind of spreading code is transmitted to the basestation through the reverse link (steps S44 and S47).

Fifth Process

In the base station, a forward link signal from the mobile station isreceived and the receiving signal is subjected to despread and decodingprocesses to reproduce transmitting symbols. Thereafter,channel-decoding is carried out and when a resetting request is raised,a resetting value is designated and then the program proceeds to thethird process. On the other hand, in the absence of a resetting requestfrom the mobile station, the program proceeds to the normaltransmitting/receiving mode using the kind and the number of spreadingcodes which are designated by the mobile station (step S48).

As described above, in the transmitting/receiving apparatus according tothe third embodiment, by taking into account the fact that the distanceover which the electric wave delivered at the same power can propagateis shorter in the case of transmission effected using a plurality ofspreading codes than in the case of transmission effected using a singlespreading code, the mobile station presumes the quality of the forwardlink and determines the number of spreading codes assigned to theforward link and then transmission/reception is carried out between thebase station and the mobile station. In consequence, a great number ofsignals can be transmitted while satisfying the prescribed link quality.

Fourth Embodiment

In the transmitting/receiving apparatus according to the thirdembodiment, the quality of the receiving signal from the base station isexamined in the mobile station at the time that communication betweenthe base station and the mobile station is started to finally set thekind and the number of spreading codes to be assigned. But, in mobilecommunication, the mobile station moves to cause the distance betweenthe base station and the mobile station to change and in consequence,the communication quality changes every moment. In addition, as thelocation where the mobile station is present changes, the communicationquality also changes.

In a transmitting/receiving apparatus according to the fourth embodimentof the present invention, the kind and the number of spreading codes areassigned in accordance with communication quality which changes everymoment and hence the optimum kind and number of spreading codes can beassigned adaptively in the mobile station. A base station sidetransmitting/receiving apparatus and a mobile station sidetransmitting/receiving apparatus according to the fourth embodiment ofthe present invention are constructed similarly to thepreviously-described base station side transmitting and mobile stationside transmitting/receiving apparatus according to the first embodimentand therefore, the operation of the base station sidetransmitting/receiving apparatus and mobile station sidetransmitting/receiving apparatus according to the fourth embodiment ofthe invention will be described hereunder with reference to a flow chartshown in FIG. 7.

First Process

In the mobile station, a forward link signal from the base station isreceived at a time point during communication and the receiving signalis subjected to despread and decoding processes to reproducetransmitting symbols (step S61). When the number (L) of spreading codesto be assigned to the forward link is 1, the program proceeds to asecond process to be described below and when the number (L) ofspreading codes to be assigned is larger than 2, the program proceeds toa third process to be described later (step S62).

Second Process

When a predetermined time (first setting value) has elapsed followingdetermination that the number (L) of spreading codes to be assigned tothe forward link is 1 (namely, when counter value T132 first settingvalue), transmission is requested with the kind of spreading codeschanged to K and thereafter, the counter is reset (steps S63 to S65). Onthe other hand, when the predetermined time (first setting value) hasnot elapsed following determination that the number (L) of spreadingcodes to be assigned to the forward link is 1, transmission is requestedwith the kind of spreading codes kept to be one and thereafter, thecounter is incremented (steps S66 and S67). Subsequently, the programproceeds to the normal transmitting/receiving mode and the procedureends (step S69).

Third Process

Presumption of receiving quality using determination based on, forexample, CRC is performed every spreading code (step S70) to determinethe number (N) of spreading codes having receiving quality values whichexceed a prescribed value. When the determined number (N) is 0,transmission is requested with the kind of spreading codes kept to be apreset value (M) (steps S71 and S72). When the determined number (N) islarger than 0 and is smaller than the number (L) of spreading codes tobe assigned to the forward link (namely, when 0<N<L) or when thedetermined number (N) equals the number (L) of spreading codes to beassigned to the forward link and equals a maximum (Nmax) of the numberof spreading codes to be assigned to the forward link (namely, when N=Land N=Nmax), transmission is requested with the kind of spreading codesset to N (steps S71 and S73). Further, when the determined number (N) isequal to the number (L) of spreading codes to be assigned to the forwardlink and is smaller than the maximum (Nmax) of the number of spreadingcodes to be assigned to the forward link (namely, when N=L and N<Nmax),a process as below is carried out. More particularly, when apredetermined time (second setting value) has elapsed following settingof the number of spreading codes to be assigned to L (namely, whencounter value T2=second setting value), transmission is requested withthe kind of spreading codes changed to L+1 (steps S71, S74 and S75) andthereafter the counter is reset (step S76). On the other hand, when thepredetermined time (second setting value) has not elapsed followingsetting of the number of spreading codes to be assigned to L,transmission is requested with the kind of spreading codes kept to be L(steps S71, S74 and S77) and thereafter the counter is incremented (stepS78). After the above steps S72, S73, S76 and S78 end, the programproceeds to the normal transmitting/receiving mode and the procedureends (step S69).

As described above, in the transmitting/receiving apparatus according tothe fourth embodiment of the present invention, for the purpose ofmaintaining the predetermined communication quality against a change inreverse link quality due to movement of the mobile station duringcommunication, the communication quality of forward link is presumed inthe mobile station and the kind and the number of spreading codes areadaptively controlled in accordance with the presumed communicationquality. The time required for communication can be decreased byincreasing the kind and the number of spreading codes to be assignedwhen the link quality is improved.

Fifth Embodiment

In the transmitting/receiving apparatus for performing transmission andreception by using a plurality of spreading codes, only signalstransmitted by using some spreading codes cannot sometimes satisfy thequality condition depending on link conditions and the performance ofspreading codes. In this case, the efficiency will be degraded greatlyif a request for re-transmission is made with respect to all spreadingcodes.

Thus, in a transmitting/receiving apparatus according to a fifthembodiment of the present invention, it is decided every spreading codewhether a re-transmission request is to be made and only when it isdetermined that the re-transmission must be performed, a re-transmissionrequest is made to a transmission partner. A base station sidetransmitting/receiving apparatus and a mobile station sidetransmitting/receiving apparatus according to the fifth embodiment ofthe invention are constructed similarly to the previously-described basestation side transmitting/receiving apparatus and mobile station sidetransmitting/receiving apparatus according to the first embodiment andtherefore, the operation of the base station side transmitting/receivingapparatus and mobile station side transmitting/receiving apparatusaccording to the fifth embodiment will be described hereunder withreference to a flow chart shown in FIG. 8. Although control carried outin the base station will be described below, the following descriptionmay meet control performed in the mobile station if the base station isreplaced with the mobile station and the reverse link is replaced withthe forward link.

In the base station side transmitting/receiving apparatus, a reverselink signal transmitted from the mobile station sidetransmitting/receiving apparatus by using a plurality of spreading codes(first to N-th spreading codes) is received (step 101). After thereceiving signal is subjected to despread and decoding processes everyspreading code to reproduce transmitting symbols, receiving qualitypresumption based on CRC is carried out (steps S102 to S104).Thereafter, it is decided every spreading code whether the presumedreceiving quality values exceed a prescribed value and a re-transmissionrequest is not made with respect to spreading codes for which thepresumed receiving quality values exceed the prescribed value but are-transmission request is made with respect to spreading codes forwhich the presumed receiving quality values are smaller than theprescribed value (steps S105 to S108). Thereafter, information as towhether or not the re-transmission request is made is described everyspreading code in control information and is sent to the mobile station(step S109).

As described above, in the transmitting/receiving apparatus according tothe present embodiment, the receiving link quality is presumed everyspreading code and the re-transmission request is made every spreadingcode, thereby improving the transmission efficiency.

Sixth Embodiment

When voice and data are transmitted and received using a plurality ofspreading codes, there arises in voice information a soundless state inwhich no conversation is made. Since no information is transmitted inthe soundless state, the soundless state consumes time in vain.

Thus, in a base station side transmitting/receiving apparatus and amobile station side transmitting/receiving apparatus according to asixth embodiment of the present invention, data is transmitted during aperiod of the soundless state to improve the transmission efficiency.The base station side transmitting/receiving apparatus and mobilestation side transmitting/receiving apparatus according to the sixthembodiment of the present invention are constructed similarly to thepreviously-described base station side transmitting/receiving apparatusand mobile station side transmitting/receiving apparatus according tothe first embodiment and therefore, the operation of the base stationside transmitting/receiving apparatus and mobile station sidetransmitting/receiving apparatus according to the sixth embodiment willbe described hereunder with reference to flow charts shown in FIGS. 9and 10.

Although an instance where a first spreading code is assigned to voiceor data and a second spreading code is assigned to data and transmissionfrom the base station to the mobile station is effected through aforward link will be described below, the following description may meetan instance where transmission from the mobile station to the basestation is effected similarly if the base station is replaced with themobile station and the forward link is replaced with a reverse link.

In the base station side transmitting/receiving apparatus, it is decidedwhether a soundless state occurs in a reverse link signal transmittedfrom the mobile station side transmitting/receiving apparatus (step S120in FIG. 9). In the absence of the soundless state, after the firstspreading code is assigned to voice, “voice” is described in controlinformation and transmitted to the mobile station (steps S121, S124 toS126). On the other hand, in the soundless state, after the firstspreading code is assigned to data, “data” is described in the controlinformation and transmitted to the mobile station (steps S121 to S123,S126).

In the mobile station side transmitting/receiving apparatus, a forwardlink signal transmitted from the base station sidetransmitting/receiving apparatus is received and the receiving signal issubjected to despread and decoding processes to reproduce transmittingsymbols (step S130 in FIG. 10). Also, channel-decoding is effected todecode the control information (step S131). When the decoded controlinformation is described with “voice”, the receiving signal is sent to avoice codec (step S132 and S134). On the other hand, the decoded controlinformation is described with “data”, the receiving signal is handled asdata (steps S132 and S133).

Seventh Embodiment

When information requiring real time nature such as voice and data notrequiring real time nature are transmitted and received using aplurality of spreading codes, the data not requiring real time nature issometimes transmitted/received through only one of a forward link fromthe base station to the mobile station and a reverse link from themobile station to the base station. Further, when desired quality ofreceiving data cannot be maintained, a re-transmission request is made.In this case, for example, when voice is transmitted using one kind ofspreading code and data not requiring real time nature is transmittedusing two kinds of spreading codes through only a reverse link or aforward link, it is necessary to transmit control information such as arequest for data re-transmission through the forward link or the reverselink even if the data is transmitted through only a oneway link ofreverse link or forward link, as will be described below.

(1) In the Case of Transmission of Voice and Data from Base Station toMobile Station

{circle around (1)} forward link:

spreading codes for voice . . . one kind (first spreading code isassigned)

spreading codes for data . . . two kinds (second and third spreadingcodes are assigned)

{circle around (2)} reverse link:

spreading codes for voice . . . one kind (fourth spreading code isassigned)

control information for data . . . one kind (fifth spreading code isassigned)

(2) In the Case of Transmission of Voice and Data from Mobile Station toBase Station

{circle around (1)} forward link:

spreading codes for voice . . . one kind (first spreading code isassigned)

control information for data . . . one kind (second spreading code isassigned)

{circle around (2)} reverse link:

spreading codes for voice . . . one kind (third spreading code isassigned)

spreading codes for data . . . two kinds (fourth and fifth spreadingcodes are assigned)

In the transmitting/receiving apparatus according to the seventhembodiment of the invention, the number of necessary spreading codes isreduced by carrying out the following processing.

(1) In the case of transmission of data through only the forward link,spreading codes of the reverse link for transmission of data controlinformation are unneeded by making a re-transmission request through thereverse link for voice.

(2) In the case of transmission of data through only the reverse link,spreading codes of the forward link for transmission of data controlinformation are unneeded by making a re-transmission request through theforward link for voice.

This is concreted as follows.

(1) In the Case of Transmission of Voice and Data from Base Station toMobile Station

{circle around (1)} forward link:

spreading codes for voice . . . one kind (first spreading code isassigned)

spreading codes for data . . . two kinds (second and third spreadingcodes are assigned)

{circle around (2)} reverse link:

spreading codes for voice . . . one kind (fourth spreading code isassigned)

control information for data . . . mixed with voice for transmission (nospreading code is assigned)

(2) In the Case of Transmission of Voice and Data from Mobile Station toBase Station

{circle around (1)} forward link:

spreading codes for voice . . . one kind (first spreading code isassigned)

control information for data . . . mixed with voice for transmission (nospreading code is assigned)

{circle around (2)} reverse link:

spreading codes for voice . . . one kind (third spreading code isassigned)

spreading codes for data . . . two kinds (fourth and fifth spreadingcodes are assigned)

A base station side transmitting/receiving apparatus and a mobilestation side transmitting/receiving apparatus according to the seventhembodiment of the present invention are constructed similarly to thepreviously-described base station side transmitting/receiving apparatusand mobile station side transmitting/receiving apparatus according tothe first embodiment and therefore, the operation of the base stationside transmitting/receiving apparatus and mobile station sidetransmitting/receiving apparatus according to the seventh embodimentwill be described hereunder with reference to a flow chart shown in FIG.11 and frame formats shown in FIGS. 12A-12D.

As an example, an instance will be considered where voice and data aretransmitted from the base station to the mobile station through aforward link and voice is transmitted from the mobile station to thebase station through a reverse link. In the forward link, the firstspreading code is assigned to voice and the second and third spreadingcodes are assigned to data and in the reverse link, the fourth spreadingcode is assigned to voice (see FIGS. 12A-12D).

The following description may meet an instance where transmission fromthe mobile station to the base station is carried out if the basestation is replaced with the mobile station and the reverse link isreplaced with the forward link.

First Process

In the mobile station side transmitting/receiving apparatus, a forwardlink signal transmitted from the base station sidetransmitting/receiving apparatus is received and the receiving signal issubjected to despread and decoding processes using the first spreadingcode to reproduce transmitting symbols (voice and controlinformation)(step S150). The receiving signal is also subjected todespread and decoding processes using the second spread code toreproduce transmitting symbols (data and control information) (stepS151). Quality of the transmitting symbols reproduced in step S151 ispresumed (step S152) and then, it is decided whether the presumedquality values exceed a prescribed value and whether a re-transmissionrequest is to be made (steps S153 to S155).

Subsequently, the receiving signal is further subjected to despread anddecoding processes using the third spreading code to reproducetransmitting symbols (data and control information) (step S156). Qualityof the transmitting symbols reproduced in step S156 is presumed (stepS157) and then it is decided whether the presumed quality values exceeda prescribed value and whether a re-transmission request is to be made(steps S158 to S160).

Subsequently, information concerning the presence or absence of therequest for re-transmission of the second spreading code and thepresence or absence of the request for re-transmission of the thirdspreading code is described in the reverse link control information (seeFIG. 12D) and the reverse link signal (voice) using the fourth spreadingcode is transmitted to the base station (step S161).

Second Process

In the base station side transmitting/receiving apparatus, the reverselink signal transmitted from the mobile station sidetransmitting/receiving apparatus is received and then the receivingsignal is subjected to despread and decoding processes using the fourthspread code to reproduce transmitting symbols (voice and controlinformation). The reproduced control information is channel-decoded andthe presence or absence of a request for re-transmission of the secondspreading code and the presence or absence of a request forre-transmission of the third spreading code are examined. In thepresence of the re-transmission request, re-transmission is effected.

What is claimed is:
 1. A transmitting/receiving apparatus for performingtransmission and reception of voice required of real time nature anddata not required of real time nature by using a plurality of spreadingcodes, comprising: means for designating more spreading codes fortransmission of the data than for transmission of the voice to a forwardlink from a base station to a mobile station; and means for transmittinga control signal for a request for retransmission of the data by using areverse link for voice from said mobile station to said base station. 2.A transmitting/receiving apparatus for performing transmission andreception of voice required of real time nature and data not required ofreal time nature by using a plurality of spreading codes, comprising:means for designating more spreading codes for transmission of the datathan for transmission of the voice to a reverse link from a mobilestation to a base station; and means for transmitting a control signalfor a request for retransmission of the data by using a forward link forvoice from said base station to said mobile station.